Speed

Speed allows you to break one of the fundamental rules of the game. Normally when you play a troop, it cannot attack on the same turn that it came into play. Speed runs right by that rule and allows the troop to attack immediately. This keyword gives you a huge chance to surprise people. Most opponents will try to plan ahead for the troops they see in play. With Speed though, that goes right out the window and you can really push through a great deal of damage if they are not ready for it!

Speed plays very aggressively, which is the nature of the mechanic. I would recommend looking for troops with Speed for those players that are looking to finish off an opponent as soon as possible.